Starter switch



Patented July 1, 1941 UNITED STATES PATENT OFFICE 2 Claims.

The present invention relates to switches of the type for starting gaseous discharge devices and is a continuation in part of patent application, Serial No. 342,213, filed June 25, 1940, Patent 2,236,671, April 1, 1941.

' Special objects of the invention are to improve the operating characteristics of switches of the type mentioned, particularly in respect to quicker operation and at lower voltage.

General objects of the invention are to provide a starter or glow switch which will be practical and reliable and at the same time be of simple, inexpensive construction.

The foregoing and other desirable objects are attained by the novel features of the invention hereinafter defined, illustrated in the accompanying drawing and broadly covered in the claims.

The drawing accompanying and forming part of the specification illustrates one of the present practical commercial embodiments of the invention. Structure and composition, however, may be modified as regards this particular illustration, all within the true intent and broad scope of the invention as hereinafter defined and claimed.

In the drawing the single illustration is a broken part sectional view of one of the new switch constructions.

The structure shown is similar in mechanical details to those shown and described in co-pending patent applications, Serial No. 342,213, filed June 25, 1940, and Serial No. 352,986, filed August 17, 1940, comprising in combination, a looped bimetallic switch contact I and a contact 2 positioned to be engaged by the expanding arm of the first contact, these being sealed within a glass envelope 3, supported within a housing or case 4.

The wires or rods 5, 6, which carry and partially form the switch contacts are shown as extending outside the envelope and secured to the buttons or studs 1, 8 which are shaped to form the terminals 9, 10 of the switch unit.

The case or can as it is frequently called may be of metal with an insulating lining, as in the second patent application above-identified, but it is now preferred to make this casing in one piece, of molded plastic insulating material, such as illustrated, with an end closure ll of the same material secured as by pins or other suitable fastenings l2 and forming an insulating mount for the switch terminals.

The switch contacts preferably are of unlike materials.

Thus, the relatively fixed switch contact 2 may be of nickel and the bimetallic switch contact I be made of strips of steel and nickel, and iron, nickel, chromium alloys, ,the steel-nickel alloy strip being at the outer side of the loop to make engagement with the nickel terminal.

The bimetallic contact or so-called bimetal may be left plain or bright as it is usually termed.

The stationary contact is shown as extended across the end of the bimetal and provided with a getter tab 13. Barium-magnesium (approximately magnesium and 25% barium) is preferred as the getter material and preferably is placed so that the getter flash will be directed downward or toward the bimetal.

For switches on the order of -watt ratings, it is preferred to use an atmosphere of commercially pure helium in the envelope and at a pressure of about 3 to 5 centimeters, or within the range of from 1 to 6 centimeters.

The particular combination disclosed provides a fast acting switch, operating at low voltage and without burning or fusing of the contacting areas of the switch elements. Glow switches of this character, furthermore, can be readily produced in quantity at low cost. The special combination disclosed, furthermore, requires no associated condenser or other accessories.

The insulating case of molded plastic is advantageous for practical reasons. Preferably it is made with an outwardly expanded or enlarged rim l4, knurled or roughened as indicated, to provide a good finger grip for entering the switch unit in or removing it from the socket with which it is usually associated.

What is claimed is:

1. A starter switch for gaseous discharge devices, comprising a sealed envelope, an atmosphere of substantially pure helium sealed in said envelope, a plain uncoated bimetallic switch element sealed in said envelope, a second relatively stationary switch element sealed in said envelope for engagement by said bimetallic switch element, a tab carried by said second switch element in opposition to said bimetallic switch element and barium-magnesium on the face of said tab opposed to said bimetallic switch element.

2. A starter switch for gaseous discharge devices, comprising a sealed envelope, an atmosphere substantially of helium sealed in said envelope, a plain uncoated bimetallic switch element sealed in said envelope, a second relatively stationary switch element sealed in said envelope in cooperative relation to said bimetallic switch element, a tab mounted in said envelope in opposition to said uncoated bimetallic switch element and barium-magnesium on the face of said tab opposed to said bimetallic switch element.

CHARLES CHIRELSTEIN. 

